The present invention relates to an image generation method, program and information storage medium.
In the prior art, an image generating system (or game system) for generating an image visible from a virtual camera (or a given viewpoint) in an object space which is a virtual three-dimensional space is known. It is highly popular as a method by which a so-called virtual reality can be experienced. In such an image generating system, it is desired that even plants including trees can realistically be represented (see Japanese Patent Application Laid-Open No. 2002-24858).
However, a conventional L system required a complicated process to generate images of trees (which, in a broad sense are plants).
A technique of representing a tree by fixedly arranging dome-shaped branch part objects around the trunk part object in all directions may be conceived. However, so many branch part objects are generated with such a technique that substantial storage capacity of a memory is required.
Another technique of representing a tree by mapping image textures of the tree on a flat plate-shaped polygon, which is known as “billboard” technique may also be conceived. In such a “billboard” technique, however, if the hidden surface removal is carried out by Z buffer, the moment when a flat plate-shaped polygon is positionally replaced by another flat plate-shaped polygon will be noticeable. This will degrade the generated image.